Apparatus for drawing sheet glass



April 13 1926. I IR. PM NAILL EFQ..JR

APPARATUS FOR DRAWING SHEET GLASS- Original Filed May 9 1923 3 Sheets-Sheet 1 Judah,

April 13,1926. 1,580,150

I R. A. MILLER, JR

APPARATUS FOfi DRAWING SHEET GLASS Original Filed May 9, 1923 3 Sheets-Sheet 2 FIE.Z.

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A ia 13,1926. 1,580,150

R A MILLER. JR

APPARATUS FOR DRAWING SHEET GLASS Original Filed May 9, 1923 3 Sheets-Sheet .3

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0v VENTOR Patented Apr. 13, 1926.

ROBERT MILLER, 33., OF TABENTUI, PENNSYLVANIA, ASSIGNOR T PITTSBURGH FLAT]! GLASS GOHPANY, A COBI'ORATION OF PENNSYLVANIA.

AZPPARATUS r03 DRAWING sneer eL'Ass.

I Applicstionnled May 8, 1928;8er1a1 No. 637,640. Renewed October 16, 1925.

To all'whom it may concern:

Be itlot own that I, ROBERT A. MILLER, J r., a citizen of the United States, and a resident of Ta'rentum, in the county of Allegheny and State of Pennsylvania, have made a new and useful invention in Improvements in A paratus for Drawing Sheet Glass, of whlch the following is a specification,

The invention relates to apparatus for drawing glass in sheet form. 'It has for its principal objects the provision of an im proved construction in which the thickness of the sheet may be regulated by varying the degree of immersion of the slot members; in which, a relatively high speed of drawmg is permissible; and in which the lining of the sides of the sheet incident to drawn from a cla slot is reduced or en.- tirely e iminated. ertain embodiments of the invention are illustrated in the accompanying drawings wherein: V

Figure 1 is an assembly view showing the apparatus in longitudinal section. Fig. 2 is a transverse section on the line II--II of Fig. 1. Fig. 3 is a plan view of the slot members on an enlarged scale. Fig. 4 is a longitudinal section on the line IVIV of Fig. 3. Fig. 5 is a transverse section on the line V-V of Fig. 3, and Fig. 6 is a transverse section through a modification. Referring to the drawings, 1 is the draw ing tank or extension carrying the molten bath of glass 2 in connection with a suitable melting tank 3; 4. and 5 are endless belts preferably of asbestos fabric for continuously drawin the sheet of glass 6 from the molten bath and 8 are driving pulleys for the belts, such belts being driven from a suitable motor (not shown) 9 and 10 are steel bars, circular in cross section lying in the lower ends of the belts and serving by reason of their weight tohold the belts in tension; 11 are a series of rolls back of the inner fiigl' ts of the belts for pressing the belts against the glass, such rolls being yieldingly held inward by means of the weights 12; 13 and 14 are 'pairs of drive-n floating rolls covered with asbestos for assisting in the'pullingof the sheet; 15 is the top wall of the furnace carried on the frame 16 which in turn is carried by theI beams 16; 17 are cables attached to the ends of the beams 16 and extending up over pulleys (not shown) on the superstructure whereby the top wall 15 may be moved up and down; 18 is a clay slot member supported from the top wall,

15 19 is a metal slot member lying inside the member 18 and sup orted from the framework 20 also carried y the framework which supplorts the top wall 15.

T e slot member 18 is provided with a longitudinal slot 21 and surfaces 22 for engaging the metal slot member 19. This slot member 19 is preferably made of heat resisting material such as IIICkGlOI nichrome, although it may be made of steel or cast iron.

It is provided with the longitudinal slot 23 lying above the slot 21 and has side walls 24 which extend upward above the surface of the glass a substantial distance, preferalfly from 8 inches to 10 inches. These side walls extend upward vertically and then taper inwardly towards each other to the at one end and the outlet coup1ing'29 at the other, so'that fluid may be circulated through the chamber in such manner as to give the desired coolin effect. The lower portion of the side wa ls 2 1 which contact with the glass may beroughened as indicated at 30 in Fig. 4-. This roughening may be accom-. plished in any desired manner, as by rou h filing or knurling, or it may be produced y lightly scoring the surface with a suitable machine tool. In order to lift the metal slot member to and from position in the member 18, the lugs 31 are brazed tothe inner surface of the outer wall and suitably'tapped to receive the bolts 32 which are attached to the framework 20.

In starting the operation a metal bait is dipped into the bath in the slot 23 and drawn upward to produce the sheet 6, after which the sheet is carried betweenthe continuous tively hi gh drawing rolls and endless curtains and the bait is cracked orv broken away. The glass which is pulled over the roughened surfaces 30 soon forms a glaze upon these surfaces when such surfaces are not chilled to too great an extent. and as a result the side surfaces of the glass formed are relatively tree from the lines which are ordinarily present when glass is drawn from con act with a clay or metal surface. If the slot member is chilled to a high degree, as may he done by using water as the cooling fluid, the surfaces will not glaze to any extent, but the roughening is still of value as it imposes a drag upon the glass and tends to give a sheet of more uniform flatness and thickness than would otherwise be the case. The glass lying in the slots 21 and 23 is chilled so that a rela- I speed of draw may be obtained without thinning the sheet to too great an extent. The sides 24: and 26 of the metal slot lying above the surface of the glass act as reflectors so that the heat trom the glass bath beneath is applied to the sides of the sheet to give it a tire finish and eliminate any lines which are formed by reason of the fact that the glass is drawn from close proximity to the clay and metal immersed in the glass. By lowering the slot members 18 and 1, a greater chilling effect is secured upon the glass lying in the slot 23 so that a thicker sheet may be produced without reducing the speed of draw. A. method is thus provided for regulating the thickness of the sheet independent of the speed of draw.

Fig. 6 illustrates a modification of the metal slot member, the clay member 18 be ing the same as in the construction of F 1. In this form of device. the chambers 223 extend the full height of the metal slot member and are cooled by applying; fluid through the connections 34 and What I claim is:

1. In glass drawing apparatus employing a glass bath from which a sheet o'lglass is to be drawn. a refractory member provided with a slot lying in the glass, a metal memher having a slot portion lying in the bath above the slot in the refractory member with the sides of said slot portion. over which the sides of the glass sh i t are drawn roughened, and means for coding the portion of the metal slot member in contact with the glass.

2. In glass drawing apparatus employing a glass bath from which a sheet of glass is to be drawn. a refractory member provided with a slot lying in the glass. :1, metal mom bcr having a, slot portion lying in the bath above the. slot-in the refractory member with the sides ol' said slot, portion, over which the sides of the glass sheet are drawn, roughened, and entered with a thin coating of hardened glass. and means for cooling the portion of the metal slot member in contact with the glass.

S. In glass drawing apparatus employing a glass bath from which a sheet of glass is to be drawn, a refractory member provided with a slot lying in the glass, a metal member having a slot portion lying in the bath above the slot in the refractory member, reflecting members extending, upward substantially vertically from said slot portion along: the sides of the glass sheet a sub stantial distance and from edge to edge thereof, andadapted to reflect the heat from the hath against the sides of the glass sheet being drawn and means for cooling the portion of the metal slot member in contact with the glass.

4t. 1n glass drawing apparatus employing a glass bath from which, a sheet of glass is to be drawn, a refractory member provided with a slot lying in the glass, and a metal slot member lying in the bath above the slot in the refractory member and having the sides tapering toward each other as their distance from the bath increases.

5. In glass drawing apparatus employing a lass bath from which a sheet ot glass is to be drawn, a refractory member provided with a slot lying in the glass, a metal slot member lying in the bath in the refractory member and having its sides tapering toward each other as their distance from the bath increases and means for cooling the metal slot member.

6. In glass drawing apparatus employing a glass bath from which a sheet of glass is to be drawn, a refractory member provided with a slot lying in the glass, and a metal slot member lying in the bath above the slot in the refractory member and having its lower portion provided 'with cooling means and with the side walls above the bath ta.- pering inward as their distance from the bath increases.

7. In glass drawinw apparatus employing a glass bath from wiich a sheet of glass is to be drawn, a refractory member provided with a slot lying in the glass, and a metal slot member having its lower portion cooled artificially and lying in the above the refractory member, and having a pair of reflectors extending; upwardly substantially vertically from said lower portion on opposite sides of the glass sheet being drawn and from edge to edge thereof.

8. In glass drawing apparatus employing a glass bath from which a sheet of glass is te'i be drawn, a re l'ractory member provided with a slot lying in the glass, a metal member having a slot portion with vertical opposing side walls lying in the bath above the slot in the rel'rartory member, substan-. tially vertical reflecting members co-cxtcn sire in length with said slot extending upstgless hath'from w ich a sheet of glass is to he'drawn, a refractory member provided with a slot lying in the glass, a metal memher'hevin a slot portion with vertical opposing si e walls lying in the bath above 10 the slot in the refractory member, substantially vertical reflecting members co-extensive in length with said slot extending up-v wardly from said side wall, and flaring outwardly at their upper portions, and means for cooling the portion of the metal member in contact with the glass.

' In testimony whereof, I have hereunto ubscribed my name this 21st day of April,

ROBERT A: MILLER, JR 

